Milling preparation: Covering areas

I want to prepare a part for milling and quickly cover several areas so that the tool doesn’t plunge into the material. However, some of these areas are very complex. What should I do?

It's best to use the SURFEXT / FILL function for this. You can use this function to create free-form surfaces which optimally fit the corresponding boundary conditions. To achieve the best possible result, we recommend the following procedure: Fill as many areas as possible with the base surface from an adjacent surface. Check the remaining areas to see if they can be filled with tetragonal surfaces.
Finally, use n-gons to fill all areas that cannot be filled with the base surface from an adjacent surface or with tetragonal surfaces.
You can also use additional connecting curves to structure the areas to be filled in order to optimize the result from this sequence.

Here's how you do it

1.

Select the SURFEXT / FILL function and select the topology with the holes you wish to fill. The FILL SURFACES dialog opens.
The desired option is selected by clicking one of the first three buttons in the upper area of the dialog. The sequence recommended in the above procedure is shown here from left to right: "Apply adjacent surfaces", "Fill tetragons" and "Fill n-gons".

2.

In this example, we first check whether there are areas that can be filled with the base surface from an adjacent surface. This is done by clicking "Apply adjacent surfaces". All of the areas that can be filled with this option are shown with a green border.

3.

Since we want to fill all of the green-bordered areas with this option, we select these areas in the display window and click APPLY. The areas are filled accordingly

4.

Since there are no areas with four boundary curves, we select the "Fill with n-gons" option in the next step. The only remaining contour is completely bounded in green, i.e. it forms a single n-gon. However, this "remaining contour" is too complex to be satisfactorily filled with a surface. We therefore first subdivide the areas with connecting curves to possibly enable several of the surfaces to be filled with tetragonal surfaces.

5.

This is done by clicking "Generate connecting curve" in the middle of the dialog. All curve elements on which you can place start and end points for the connecting curve are shown in green. For each curve, we select the start and end points and click "APPLY". The corresponding connecting curves are generated. Each curve can be modeled as desired.

6.

Once all of the curves have been generated, we select the "Filled with tetragons" option. All of the areas that can now be filled with tetragonal boundary curves are displayed. We select all of the areas shown in the display window and click APPLY. If necessary, click the "Transition" button to toggle between continuous and tangential transitions.

7.

Then we again select the "Fill with n-gons" option. Select the remaining areas to be closed and click APPLY. All areas to be closed in our example are now filled. If necessary, click the "Transition" button to toggle between continuous and tangential transitions.

Hints

To achieve the best possible transitions, first fill the larger areas wherever possible and then the smaller areas.

Use the Tebis multi-select functions such as the Trap function to select several areas at once in the display window.

Open the context-sensitive help in the SURFEXT/FILL function to find more information about creating fill surfaces.

Open the context-sensitive help in the SELECT area for more information on the multi-select functions.

Contact

Ulrike Keller

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